Enquêter sur le Mystère de l'Abbaye

Crypta - "play again" is definitely a powerful effect; it can give you the advantage you need in the final rush to the Capitulum (sometimes many players discover the culprit at the same moment: maybe because of the "dance of the cards" during Mass or because of the answer to a critical question). Besides, the simple possibility to move 4 squares if desired, is usually enough to keep the opponents away from your Cell (if necessary, reminds them that you COULD move so much, if only they're so eager to do penance).

Confessionals & Cells - "steal a card" is an interesting option, especially at the beginning of the game (later your chance to draw a card you already know is so high that you probably have better options). The best targets are: the player after you (because you'll pass him the card you've stolen during Mass, effectively reducing his gain of information) and the player opposed to you (because he's the player you have less interaction with during Mass, so your chances to steal something useful are higher).
Note that the outer confessional is better than the other (it allows you to reach Parlatorium or Scriptorium in 2 turns instead of 3).
Never visit a Cell if you risk to be caught (look at the Crypt cards!): losing a turn to penance (and the card in hand) is a price too high for a single peek (that could be useless).

Parlatorium - the strongest location after Library. You get a card not seen by anyone (excellent choice for "the card I'll try to never show to anyone, so they won't be sure about the assassin") and your hand size grows (something useful to keep a certain card or two hidden as long as possible during Masses). When cards are all drawn, you still have a powerful option: "show me a card so and so" is something like an unstoppable question (of course you're a bit limited, but that's just fair); it maybe the best way to discover those cards everyone is keeping hidden from the beginning of the game.

Scriptorium - a really random location: some books can be very useful, but sometimes you've just wasted your turn (some books have a very narrow use). You should try to visit Parlatorium rather than Scriptorium, unless a player is in the Scriptorium, none is in the Parlatorium and you guess no one is going to visit the Parlatorium OR you have the right to visit the Library (in this case consider the Scriptorium as a "bonus" on the way to reach your real objective).

Library - insane. As soon as you can, visit it! There are some books that can almost win the game for you (you accumulate so much news in just a turn!). You risk getting one of the minor effects ("Play again, moving anywhere") but they aren't too bad in any case (and you have to dare if you wish to read the powerful tomes).
When you want a more strategic game you really have to close the Library (alternatively, remove from the deck "Mirror of the World" and "Gospel of Judas"; unless you're playing with 6 players they are game-breaking... and if you're playing with 6, the game isn't very strategic in any case).

Capitulum - revelations are weak. Two right revelations still lose to the right accusation (due to the tie-breaking rule) and if you're able to make three right revelations you should know the assassin. If you try random revelations your chances to get 6 points are as low as 12,5%... not reliable (and not fun). Go to the Capitulum only for the accusation (and remember Rule #4).

About Capitulum Location:
If revelations are weak as you say, and I agree, there is no point in making them so there is no point such an option is present in the game. Instead, i suggest one thing to recover from the tie 4 vs 4 points when a correct accusation is done.
When someone is about to accuse, if there is another player that has made 2 revelations he can SECRETLY make an accusation. If his 2 revelations (2+2) and his secret accusation is correct , he gains +1 point of being able to guess who murdered Adelmo. So in this particular case there won't be a tie but a 5-4 in favor to the revelation strategy guy.
This will make more sense. Since you practically loose turns by doing revelations to earn points I think is fair to apply this rule. He still won't be sure 100% who the murder is but gives him a chance (remember, if his 2 rev are correct too) to win. It also make the player who's going to the capitulum to accuse without previously revelations made be scared to do it, and he might want to do just one revelation before to be sure to earn 6 total final points.

Note: if you are doing revelations I'll suggest to go for that way (since you 'll gather less infos too due to turns spent to reach the capitulum) ! I think who's going for this strategy should aim to do 3 correct revelations always. That will be the best way to earn 6 points and it's a pretty solid base to win. If you do 2 revelations and then just spend your time to figure out who's the murdered you might don't do that in time. Instead, trying to find out 3 correct revelations its easiest.